I think it's fairly pitiful that the forum doesn't get a reply from Canon, it doesn't make sense that they'd prefer a raft of calls about the same issue rather than posting a single answer to the forum. I have an MF753Cdw color laser printer and it does this a few times a day. Given the noise it makes I expect it's rotating pressure rollers to keep them from deforming after long periods of inactivity. However, I don't know a great deal about how these printers work, and performing a pre-charge, as was mentioned earlier in the thread, also seems like a reasonable possibility. In any case, this is by design and is not a problem.
